President Trump has confirmed he will use emergency powers to build a wall on the US border with Mexico, saying "walls work". Building the wall was a key pledge of Mr Trump's campaign, but Democrats have described the move as a "gross abuse of power". He later signed the plan along with a spending bill aimed at preventing a repeat of a recent government shutdown. He announced the plan after Congress refused to pay for a wall in the bill.

Senior Democrats immediately said that they would challenge the move in the courts. The declaration will give Mr Trump access to billions of dollars for his project. Making the announcement in the White House Rose Garden, the president said the emergency would allow him to get almost $8bn for the wall. The money is expected to be diverted from military construction projects and efforts to fight the drugs trade. This is still considerably short of the estimated $23bn cost of the wall along almost 2,000 miles (3,200km) of border. “We’re going to confront the national security crisis on our southern border,” Mr Trump said.

“We have an invasion of drugs, invasion of gangs, invasion of people, and it’s unacceptable. “Everyone knows that walls work.” But Mr Trump accepted that he would be sued for the move, and predicted that the emergency order would lead to legal action which was likely to end up in the Supreme Court.

Within hours, the first legal challenge against the declaration of national emergency was launched. A liberal advocacy group, Public Citizen, sued on behalf of a nature preserve and three Texas landowners who have been told the wall may be constructed on their properties.